I think it was a bit of that, mixed with the iPhone launch and subsequent release of the App Store and third-party apps. Limiting app development and distribution exclusively to Macs through Xcode probably forced a lot of people into using them for the first time. Mac OS X also received UNIX certification around this time IIRC, I wouldn't be surprised if that compatibility pushed some more people tired of fiddling with their OS towards the "it just works" Mac.